On Tuesday 15 October Natural England granted a licence to permit the exclusion of bats from the interior of St. Hilda's Church at Ellerburn in the North York Moors. This follows a research project over the summer that was instigated and sponsored by Natural England. The research was carried out by the National Wildlife Management Centre at the Animal Health & Veterinary Laboratories Agency.

The church supports roosts of Natterer's, Brown Long-eared, Whiskered and Common Pipistrelle bats. All of these bats roost within the roof of the church. The Natterer's and Brown Long-eared bats fly within the church. During these flights the bats deposit droppings and urine over the interior of the building which the congregation find unacceptable. Consequently, the church has run a lengthy campaign to have the bats excluded from the interior of the building. North Yorkshire Bat Group has opposed this throughout because we believe that exclusion of the bats from the interior is likely to result in them abandoning the church entirely.

The research carried out this summer found that the building was used by about 20 Brown Long-eared and 200 Natterer's bats. Whiskered and Common Pipistrelle bats were not included in the research because they do not generally fly inside the church and so would not be affected by any exclusion. In 2013 Brown Long-eared bats left the building prior to breeding, but Natterer's bats bred at the site.

The research showed that all bats can reach their roost sites directly from the outside without needing to travel through the church building. However, a significant number of bats fly inside the church before emerging to the outside in the evening. Both Brown Long-eared and Natterer's bats frequently exhibit this behaviour at roosts where they are able to access the inside of a building in which they roost. The reasons for the behaviour is not understood, nor is it known if all bats in a roost do this, or if it is a particular subset of the population. However, there are a number of examples where bats prevented from flying inside the building have abandoned roosts entirely.

The licence granted does include monitoring the impacts of the exclusion for the next five years and includes provision for reversing the exclusion should the bats abandon the building and not be shown to have found an alternative roost site (no other significant roost sites were found during the research this summer). We also have concerns over the limited nature of any reversal and that the timing of monitoring in 2014 needs to be extended earlier into the spring. This is necessary because in a normal spring bats would be expected to return in April or May. If at that stage they abandoned the roost, monitoring starting in June would be unable to locate them or determine whether they had found another roost site.

North Yorkshire Bat Group has made detailed comments to Natural England and has asked for amendments to be made to the exclusion process, monitoring timetable and reversal plans should the bats abandon the roost. We will be closely following the case and will report back again once monitoring has begun.